A broad range of light sources are available for artificial lighting, for example, incandescent bulbs, fluorescent bulbs, metal halide lamps, mercury lamps, and halogen lamps. These lighting devices, however, are in common in over-consumption of electricity, and such hazardous materials as mercury may involve the risk of environmental disruption. In fact, all of the artificial lighting devices currently used worldwide involve some kind of ecohazard in varying degrees, which leads to the prospect such artificial lighting devices historically available will eventually be banned from being used.
Under the circumstances, it is being said that alternatives to the existing artificial light sources; FEL (Field Emission Lamp, which in this description refers to lighting devices using luminous elements made of diamond), LED (Light Emitting Diode), and organic EL (Organic Electro Luminescence), will one day be conveniently used for different purposes that are suited to their advantages.